Salient Features of Functional Neurological Disorder (Hysteria)
Functional neurological disorder is characterized by motor or sensory symptoms that demonstrate clinical incompatibility with recognized neurological conditions, diagnosed through positive neurological signs rather than by exclusion or psychological factors alone. 1
Core Clinical Features
Primary Symptom Categories
The disorder presents with altered voluntary motor or sensory function across three main classifications 1, 2:
Motor symptoms:
- Weakness with characteristic "giving-way" pattern
- Movement disorders including tremor, jerks, and dystonia
- Contractures and spasms
- Peculiar distributions of weakness that don't follow anatomical patterns 3
Sensory symptoms:
- Anesthesia and sensory disturbances
- Sensory loss patterns inconsistent with neuroanatomical distributions
Paroxysmal manifestations:
- Seizure-like events (dissociative/non-epileptic seizures)
- Major and minor hysterical attacks
- Syncope and tetany
- Cataleptic attacks 2
Associated Features
Commonly co-occurring symptoms that significantly impact quality of life 1:
- Persistent fatigue
- Chronic pain
- Cognitive deficits (consciousness, memory issues)
- Speech and swallowing symptoms
Critical Diagnostic Approach
Positive Neurological Signs (Most Reliable)
The diagnosis must be made actively based on positive signs of incompatibility, not by exclusion 4, 3. Key examination findings include:
- Hoover's test for lower limb weakness
- Sonoo abductor test for detecting nonorganic paresis
- Signs revealing nonorganic etiology through synergy testing 3
- Neurological inconsistencies on physical examination 5
Important Diagnostic Pitfalls
Avoid these common errors:
- Extensive exclusive diagnoses and over-investigation prolong disease course and fix symptoms 3
- Do not rely on psychological explanations as diagnostic criteria—they are unreliable 3
- La belle indifference (absence of distress) is NOT required for diagnosis and may be absent more commonly than previously believed 6
- The disorder can coexist with organic neurological disease 5
Clinical Impact and Burden
Patients experience 1:
- High levels of distress and disability
- Frequent unemployment and loss of employment 7
- Reduced quality of life
- High social care utilization
- Significant stigma contributing to disease burden
- Long periods of misdiagnosis 7
Presentation Patterns
Temporal characteristics:
- Symptoms can present acutely and resolve quickly
- Or become long-lasting and chronic
- Often occur during times of high psychological stress 6
Risk factor assessment should be performed early in the patient encounter to reduce unnecessary testing 6.
Modern Conceptual Framework
The disorder operates within a biopsychosocial aetiological framework 1, representing a shift from purely psychological interpretations. The DSM-5 marked a significant break from requiring identification of psychological factors for diagnosis 2, 8, emphasizing instead the neurological signs themselves as diagnostic criteria 4.